Clavicle - Wikipedia
Download scientific diagram | Relation between scapula, clavicle, and manubrium for a Gibbon clavicle (full line) and that for a great ape (dotted line). Main outcome measurements Three-dimensional scapular resting alignment was measured with 3D motion-capture system. The scapular resting alignment was. This is a tutorial on the shoulder girdle. The shoulder girdle consists of the scapula at the back and the clavicle anteriorly. The shoulder girdle is also referred to.
A strong outside force in this area can cause the head of the humerus to slip out of the glenoid socket, called dislocation. Since there is little bony stability in this joint, a number of ligaments and other soft tissues stabilize this joint. The superior AC ligament is the most important horizontal stabilizer.
The coracoclavicular ligaments help stabilize the clavicle vertically. The Sternoclavicular Joint SC Most of the rotation occurs at the sternoclavicular joint and joint stability comes from the soft tissues.
The posterior sternoclavicular joint capsule is the most important structure for preventing forward and backward displacement of the medial clavicle. The Rotator Cuff The rotator cuff consists of four muscle-tendon units that originate on the scapula and attach to the tuberosities of the humerus.
The rotator cuff is the primary stabilizer during movement of the GH joint. Both overuse and traumatic injuries to the rotator cuff are the most common problems in the shoulder girdle.
Scapula and Clavicle - Shoulder Girdle • Musculoskeletal, Skeletal • AnatomyZone
The Subacromial Space The subacromial space is beneath the acromion and above the rotator cuff. The subacromial bursa outlines this space and provides frictionless gliding of the rotator cuff beneath the arch formed by the acromion and coracoacromion. Bone spurs on the underside of the acromion narrow this space, irritate the bursa and contribute to tears in the rotator cuff. Bones of the Shoulder Girdle Click on image for larger labeled, picture.
The bones of the shoulder girdle include the humerus, the scapula, and the clavicle. There are four articulations movements in the shoulder named for their anatomic locations: The scapula is the most complex of the bones in the shoulder and is part of the shoulder girdle.
The scapula floats on the rib cage, and is attached to it only with muscles. There are three landmarks on the scapula; the spine, acromion and coracoid processes. The roof of the glenohumeral joint is formed by the acromion. The acromion articulates with the clavicle forming the acromioclavicular AC joint. A spine divides the back of the scapula into two sections.
The muscles that attach below this spine are called infraspinatus muscles; the ones that attach above this spine are called supraspinatus muscles. The humerus is the ball part of the ball-and-socket joint.
The head ball of the humerus articulates within the glenoid fossa. Below the humeral head is the anatomic neck which separates the head ball from the tuberosities. Each tuberosity provides a place for the attachment for the anterior muscles of the rotator cuff—the 4 rotator cuff muscles originate from the scapula and their tendons attach at the humerus.
The bicipital groove separates the tuberosities. Just below the tuberosities is the surgical neck of the humerus and is the most common area for fractures of the proximal humerus.
Clavicle Shoulder Blade — lateral view Clavicle collar bone.
The clavicle originates at the sternum breastbone just above the first rib, and is held in place by the acromioclavicular ligament, several muscles and the coracoclavicular ligament. The clavicle helps hold the shoulder out to the side while allowing the scapula to move around.
Shoulder Ligaments Click on image to see larger picture. There are several important ligaments about the shoulder girdle. Ligaments are soft tissue structures that connect bones to bones. Ligaments are strong, tough bands that are not particularly flexible. Once stretched, they tend to stay stretched and if stretched too far, they snap. Ligaments, along with muscles and tendons, are the main source of stability for the shoulder.
Shoulder ligaments also form the joint capsule that surround the glenohumeral joint. These passive stabilizers serve to keep the joints of the shoulder from dislocating.
The Scapula: How It Can Make or Break You
Some of the main ligaments are the acromioclavicular, coracoclavicular and the coracoacromial. When injured, the ligament that attaches the clavicle to the acromion—the acromioclavicular ligament—is called a separated shoulder. Two ligaments connect the clavicle to the scapula by attaching to the coracoid process—the coracoclavicular and the coracoacromial ligaments.
The coracoacromial prevents upward dislocation of the shoulder.
Scapula and Clavicle – Shoulder Girdle
Shoulder Ligaments Ligaments of the AC joint: Capsular; superior and inferior acromioclavicular; articular disk; coracoclavicular trapezoid and conoid Ligaments of the Sternoclavicular joint: Capsular; anterior and posterior sternoclavicular; inter- and costo- clavicular; articular disk Ligaments of the GH joint: The inferior surface has an oval impression inferior to its medial end for the costoclavicular ligament and is called costal tuberosity.
At the lateral side of the inferior surface, there is a subclavian groove for insertion of the subclavius muscle. At the lateral side of the subclavian groove, the nutrient foramen lies. The medial part is quadrangular in shape where it makes a joint with the manubrium of the sternum at the sternoclavicular joint. The margins of the subclavian groove give attachment to the clavipectoral fascia.
Lateral third of the shaft[ edit ] The lateral third of the shaft has two borders and two surfaces. Development[ edit ] The collarbone is the first bone to begin the process of ossification laying down of minerals onto a preformed matrix during development of the embryoduring the fifth and sixth weeks of gestation. However, it is one of the last bones to finish ossification at about 21—25 years of age.
It consists of a mass of cancellous bone surrounded by a compact bone shell. The cancellous bone forms via two ossification centresone medial and one lateral, which fuse later on. The compact forms as the layer of fascia covering the bone stimulates the ossification of adjacent tissue. The resulting compact bone is known as a periosteal collar. Even though it is classified as a long bonethe collarbone has no medullary bone marrow cavity like other long bones, though this is not always true.
Variation[ edit ] The shape of the clavicle varies more than most other long bones. It is occasionally pierced by a branch of the supraclavicular nerve. In males it is thicker and more curved and the sites of muscular attachments are more pronounced. The left clavicle is usually longer and not as strong as the right clavicle. Clavicle form is a reliable criterion for sex determination.
Functions[ edit ] The collarbone serves several functions: Acting as a flexible, crane-like strut, it allows the scapula to move freely on the thoracic wall. Covering the cervicoaxillary canalit protects the neurovascular bundle that supplies the upper limb. Transmits physical impacts from the upper limb to the axial skeleton. Muscles and ligaments that attach to the collarbone include: